From 37a7d8b046da6254718be1409140cd7bf3126f8f Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Fri, 5 Jan 2007 16:36:56 -0800 Subject: [PATCH] [PATCH] KVM: MMU: add audit code to check mappings, etc are correct Signed-off-by: Avi Kivity Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/kvm/mmu.c | 187 +++++++++++++++++++++++++++++++++++++- drivers/kvm/paging_tmpl.h | 4 + 2 files changed, 189 insertions(+), 2 deletions(-) diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index 2fc252813927..6e7381bc2218 100644 --- a/drivers/kvm/mmu.c +++ b/drivers/kvm/mmu.c @@ -26,8 +26,31 @@ #include "vmx.h" #include "kvm.h" -#define pgprintk(x...) do { printk(x); } while (0) -#define rmap_printk(x...) do { printk(x); } while (0) +#undef MMU_DEBUG + +#undef AUDIT + +#ifdef AUDIT +static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg); +#else +static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg) {} +#endif + +#ifdef MMU_DEBUG + +#define pgprintk(x...) do { if (dbg) printk(x); } while (0) +#define rmap_printk(x...) do { if (dbg) printk(x); } while (0) + +#else + +#define pgprintk(x...) do { } while (0) +#define rmap_printk(x...) do { } while (0) + +#endif + +#if defined(MMU_DEBUG) || defined(AUDIT) +static int dbg = 1; +#endif #define ASSERT(x) \ if (!(x)) { \ @@ -1271,3 +1294,163 @@ void kvm_mmu_slot_remove_write_access(struct kvm_vcpu *vcpu, int slot) } } } + +#ifdef AUDIT + +static const char *audit_msg; + +static gva_t canonicalize(gva_t gva) +{ +#ifdef CONFIG_X86_64 + gva = (long long)(gva << 16) >> 16; +#endif + return gva; +} + +static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte, + gva_t va, int level) +{ + u64 *pt = __va(page_pte & PT64_BASE_ADDR_MASK); + int i; + gva_t va_delta = 1ul << (PAGE_SHIFT + 9 * (level - 1)); + + for (i = 0; i < PT64_ENT_PER_PAGE; ++i, va += va_delta) { + u64 ent = pt[i]; + + if (!ent & PT_PRESENT_MASK) + continue; + + va = canonicalize(va); + if (level > 1) + audit_mappings_page(vcpu, ent, va, level - 1); + else { + gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, va); + hpa_t hpa = gpa_to_hpa(vcpu, gpa); + + if ((ent & PT_PRESENT_MASK) + && (ent & PT64_BASE_ADDR_MASK) != hpa) + printk(KERN_ERR "audit error: (%s) levels %d" + " gva %lx gpa %llx hpa %llx ent %llx\n", + audit_msg, vcpu->mmu.root_level, + va, gpa, hpa, ent); + } + } +} + +static void audit_mappings(struct kvm_vcpu *vcpu) +{ + int i; + + if (vcpu->mmu.root_level == 4) + audit_mappings_page(vcpu, vcpu->mmu.root_hpa, 0, 4); + else + for (i = 0; i < 4; ++i) + if (vcpu->mmu.pae_root[i] & PT_PRESENT_MASK) + audit_mappings_page(vcpu, + vcpu->mmu.pae_root[i], + i << 30, + 2); +} + +static int count_rmaps(struct kvm_vcpu *vcpu) +{ + int nmaps = 0; + int i, j, k; + + for (i = 0; i < KVM_MEMORY_SLOTS; ++i) { + struct kvm_memory_slot *m = &vcpu->kvm->memslots[i]; + struct kvm_rmap_desc *d; + + for (j = 0; j < m->npages; ++j) { + struct page *page = m->phys_mem[j]; + + if (!page->private) + continue; + if (!(page->private & 1)) { + ++nmaps; + continue; + } + d = (struct kvm_rmap_desc *)(page->private & ~1ul); + while (d) { + for (k = 0; k < RMAP_EXT; ++k) + if (d->shadow_ptes[k]) + ++nmaps; + else + break; + d = d->more; + } + } + } + return nmaps; +} + +static int count_writable_mappings(struct kvm_vcpu *vcpu) +{ + int nmaps = 0; + struct kvm_mmu_page *page; + int i; + + list_for_each_entry(page, &vcpu->kvm->active_mmu_pages, link) { + u64 *pt = __va(page->page_hpa); + + if (page->role.level != PT_PAGE_TABLE_LEVEL) + continue; + + for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { + u64 ent = pt[i]; + + if (!(ent & PT_PRESENT_MASK)) + continue; + if (!(ent & PT_WRITABLE_MASK)) + continue; + ++nmaps; + } + } + return nmaps; +} + +static void audit_rmap(struct kvm_vcpu *vcpu) +{ + int n_rmap = count_rmaps(vcpu); + int n_actual = count_writable_mappings(vcpu); + + if (n_rmap != n_actual) + printk(KERN_ERR "%s: (%s) rmap %d actual %d\n", + __FUNCTION__, audit_msg, n_rmap, n_actual); +} + +static void audit_write_protection(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_page *page; + + list_for_each_entry(page, &vcpu->kvm->active_mmu_pages, link) { + hfn_t hfn; + struct page *pg; + + if (page->role.metaphysical) + continue; + + hfn = gpa_to_hpa(vcpu, (gpa_t)page->gfn << PAGE_SHIFT) + >> PAGE_SHIFT; + pg = pfn_to_page(hfn); + if (pg->private) + printk(KERN_ERR "%s: (%s) shadow page has writable" + " mappings: gfn %lx role %x\n", + __FUNCTION__, audit_msg, page->gfn, + page->role.word); + } +} + +static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg) +{ + int olddbg = dbg; + + dbg = 0; + audit_msg = msg; + audit_rmap(vcpu); + audit_write_protection(vcpu); + audit_mappings(vcpu); + dbg = olddbg; +} + +#endif diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h index 32b385188454..c894b51ba3f8 100644 --- a/drivers/kvm/paging_tmpl.h +++ b/drivers/kvm/paging_tmpl.h @@ -355,6 +355,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, int r; pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code); + kvm_mmu_audit(vcpu, "pre page fault"); r = mmu_topup_memory_caches(vcpu); if (r) @@ -402,6 +403,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, pgprintk("%s: io work, no access\n", __FUNCTION__); inject_page_fault(vcpu, addr, error_code | PFERR_PRESENT_MASK); + kvm_mmu_audit(vcpu, "post page fault (io)"); return 0; } @@ -410,10 +412,12 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, */ if (pte_present && !fixed && !write_pt) { inject_page_fault(vcpu, addr, error_code); + kvm_mmu_audit(vcpu, "post page fault (guest)"); return 0; } ++kvm_stat.pf_fixed; + kvm_mmu_audit(vcpu, "post page fault (fixed)"); return write_pt; } -- 2.20.1